JP3465529B2 - Power control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device used in a device such as a copying machine, and more particularly to a technique capable of supporting a power saving mode at low cost.

[0002]

2. Description of the Related Art A copying machine includes a 24V load (hereinafter, this load is generically referred to as "driving system load") which operates when a DC voltage of 24V such as a DC motor is applied, and a CP.
Various electric parts and the like are used, such as a U and a memory, a 5V load that operates when a 5V DC voltage is applied (hereinafter, this load is generically referred to as a "control system load"), and the like. . Then, in the copying machine, the setting contents such as the copy magnification are stored in the memory, the CPU controls the rotation of the DC motor according to the setting contents, the copying is executed, and the number of copies is stored in the memory. Therefore, in order to reduce the waiting time due to warming up, it is desirable to constantly supply power to both loads.

On the other hand, there is a strong demand for energy saving due to the recent energy situation, and even in a copying machine which consumes a relatively large amount of power, countermeasures against it are urgently required, and power is constantly supplied to both loads even when copying is not performed. There is a tendency to review. As one of the measures, there was a plan to stop the power supply to both loads if no operation was continued for a certain period of time, but in that case, the power supply to the control system load would also be stopped, and the memory However, there is an inconvenience that the stored contents of is lost and the normal mode cannot be automatically restored.

Therefore, a relay switch is provided in the power supply path to the drive system load, and while the power supply to the control system load is maintained in the power saving mode, the relay switch is operated based on the power saving mode signal output from the CPU. Energy saving measures are taken by turning off the power and stopping only the power supply to the drive system load.

[0005]

However, since a large amount of inrush current flows through the relay switch when the relay switch of the relay is turned off or turned on, an expensive large current relay must be used. Not
There was a problem that the cost was high. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a power supply control device capable of eliminating the relay and yet being capable of energy saving while ensuring power supply to a control system load. And

[0006]

In order to achieve the above object, the power supply control device according to the present invention operates when a first DC voltage is applied and does not operate at a voltage less than the first DC voltage. A load and a second load that operates when a second DC voltage less than the first DC voltage is applied,
A power supply control device used in a device for operating both loads in a normal mode and operating only a second load in a power saving mode, and a first DC power supply means to which the first load is connected. A second direct current power supply means connected to the second load, the first direct current power supply means receiving the electric power from the first direct current power supply means. The supply voltage to be supplied to the second load and the second DC power supply means is set to the first voltage, and the supply voltage is less than the first voltage in the power saving mode, and the second DC power supply means is set to the second voltage. It is characterized in that the voltage is set to a voltage necessary to output the voltage.

Further, the first DC power supply means receives a command to increase the voltage to the first voltage in the normal mode and a command to decrease the voltage to less than the first voltage in the power saving mode. It is also possible to adopt a configuration in which a voltage control means for controlling the supply voltage is provided.

In the specification of the present application, if the load does not operate, for example, when the drive system load is the above-mentioned motor, even if a voltage is applied to the drive coil, the load does not affect the load applied to the rotating shaft of the motor. As the torque cannot be generated, the load does not exert its function even if a voltage is applied to it so that the rotating shaft does not rotate. Is used to maintain

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a power supply control device according to the present invention will be described with reference to the case where it is used in a copying machine.

(1) Overall Configuration of Power Supply Control Device FIG. 1 is a circuit diagram showing the overall configuration of the power supply control device and its vicinity. As shown in the figure, the power supply control device 1 is connected to the first DC power supply unit 100 to which the drive system load RL24 of the copying machine is connected and the power supply from the first DC power supply unit 100 to connect the control system load RL5. The second DC power supply unit 200 is provided. In the figure, the drive system load RL2
4. The control system load RL5 is shown by an equivalent resistance. The drive system load RL24 operates when a DC voltage of 24V is applied, and the control system load RL5 operates when a lower DC voltage of 5V is applied. , Drive system load RL
24 does not operate below 24V, for example 9V.

The first DC power supply unit 100 is a line-operated switching regulator that obtains 24 V in the normal mode and 9 V in the power saving mode from 100 V AC of the commercial power supply. A diode bridge 101 for rectifying and a smoothing capacitor 10 for smoothing the pulsating current waveform of the rectified voltage
2 and the primary side and the secondary side are insulated, and high frequency power is 1
The high-frequency transformer 103 that transmits from the secondary side to the secondary side, and the switching transistor 104 that converts the DC power supplied from the smoothing capacitor 102 into high-frequency power by switching at high speed and supplies the power to the primary side of the high-frequency transformer 103. A diode 105 for half-wave rectifying the high frequency transmitted to the secondary side, a smoothing capacitor 106 for smoothing the pulsating current waveform of the rectified voltage, and a drive system load R
The terminals Vout1 and GND to which L24 is connected, and the terminal Vout1
Resistors 107 and 108 for dividing the voltage between GND and outputting a voltage corresponding to the division ratio as a voltage feedback signal FB,
A relay 109 that switches the switching mode of the relay switch based on a power saving mode signal CNT output from a CPU (not shown) of the control system load RL5, and an overcurrent connected to the individual contacts a and b of the relay switch, respectively. It comprises limiting resistors 110 and 111, and a power supply control circuit 112 for controlling the voltage between the terminals Vout1 and GND to a target voltage by changing the on / off ratio of the switching transistor 104.

The power saving mode signal CNT is at the H level in the normal mode and at the L level in the power saving mode, and the target voltage is 24 V in the normal mode and 9 V in the power saving mode.

In the normal mode, the relay 109 connects the switching contact c to which the control voltages Vc and 5V output from the second DC power supply unit 200 are applied and the individual contact a based on the H level power saving mode signal CNT. It connects and outputs the control voltage Vc as a 24V output command ref1 via the resistor 110 to the power supply control circuit 112, and connects the switching contact c and the individual contact b based on the L level power saving mode signal CNT in the power saving mode. Then, the control voltage Vc is output to the power supply control circuit 112 as the 9V output command ref2 via the resistor 111.

The power supply control circuit 112 outputs a 24V output command r
ef1, 9V output command ref2, three input ports for inputting the voltage feedback signal FB, and an output port for outputting the transistor switching signal QB to the base of the switching transistor 104 are provided, and the 24V output commands ref1 and 9V are output from the relay 109. The target voltage is determined depending on which of the output commands ref2 is input, and the error between the voltage between the terminals Vout1 and GND and the target voltage is known based on the voltage feedback signal FB, and the duty ratio, frequency, etc. are changed. As a result, a transistor switching signal QB that determines the on / off ratio of the switching transistor 104 is output to the base of the switching transistor 104. As a result, the power supply control circuit 112 causes the voltage between the terminals Vout1 and GND to be 24V when the 24V output command ref1 is input regardless of the change in the load current.
When the 9V output command ref2 is input, the voltage between the terminals Vout1 and GND is controlled to be maintained at 9V.

The second DC power supply section 200 comprises a DC / DC converter 201, a smoothing capacitor 202, and terminals Vout2 and GND to which the control system load RL5 is connected.
The DC / DC converter 201 is configured using a high frequency transformer, a switching transistor, a rectifying diode, and the like like the first DC power supply unit 10, and while the first DC power supply unit 10 supplies 24V to 9V. Is
The voltage between the terminal Vout2 and GND can be maintained at 5V. Therefore, the first DC power supply unit 10 supplies the lowest voltage of 9V that the DC / DC converter 201 can maintain 5V output in the power saving mode to the DC / DC converter 20.
It is designed to supply one.

(2) Operation of Power Supply Control Device In the power supply control device thus configured, in the normal mode, the first DC power supply section 100 outputs 24V,
Since the second DC power supply unit 200 outputs 5V, both loads RL24 and RL5 to which these voltages are applied also operate. Therefore, in the copying machine, the setting contents such as the copy magnification are stored in the memory and the CP is set according to the setting contents.
Copying can be executed by a process in which U controls the rotation of the DC motor, and the number of copies can be stored in the memory.

On the other hand, in the power saving mode, the first
The DC power supply unit 100 outputs 9V, and the second DC power supply unit 20
Since 0 outputs 5V, only the control system load RL5 operates and the drive system load RL24 does not operate.

Here, the power consumption in the normal mode and the power saving mode will be considered by calculation. Drive system load RL24
Resistance value of 120Ω, control system load RL5 resistance value of 10
When Omega, the total power consumption WH drive system load RL24 and the control system loads RL5 in the case of the normal ^{mode, WH = (24 2/120} ) + (5 2/10) = 4.8 + 2.5 = 7. It becomes 3 [W].

[0019] In contrast, the total power consumption WL of the power saving mode, the ^{WL = (9 2/120)} + (5 2/10) = 0.675 + 2.5 ≒ 3.2 [W].

Therefore, in the power saving mode, the power consumption is about 43% of that in the normal mode.

[0021] In the conventional power supply control circuit, the total power consumption WL of the power saving ^{mode, WL = (0 2/120} ) + (5 2/10) = 0 + 2.5 = 2.5 [W] becomes Although energy can be saved as compared with the present embodiment, the difference is only 0.675 W and an expensive relay is required. Moreover, even in the power saving mode, the first DC power supply unit 100 to the second DC power supply unit 200
It was necessary to supply 24V to.

On the other hand, in the embodiment of the present invention, the output voltage of the first DC power supply unit 100 is reduced to 9V in the power saving mode, so that the load inside the first DC power supply unit 100 is reduced. In the power saving mode, the output voltage of the first DC power supply unit 100 is reduced, and thus the first DC power supply unit 100 is reduced.
The internal loss of can be reduced. Further, in the power saving mode, the difference between the voltage input to the DC / DC converter 201 and the output voltage becomes small, and thus the DC / DC
The internal loss of converter 201 also decreases. Therefore,
Conventionally, the relay provided in the power supply path to the drive system load RL24 can be eliminated, and the control system load RL can be manufactured at low cost.
It is possible to achieve the energy saving effect comparable to the conventional one, while securing the power supply to No. 5.

Further, although a large current relay is conventionally used, there is a possibility that the relay switch may be burned out due to an inrush current and may be kept in conduction or cut off. However, there is an inconvenience that 24V is continuously fed to the drive system load and energy saving cannot be achieved, and if it is cut off, it cannot return to the normal mode. In the embodiment, since the relay can be eliminated, such an inconvenience can be prevented, and the first DC power supply unit 10 can be prevented.
Since the output voltage of 0 is lowered to 9 V, which is lower than the conventional value, in the power saving mode, safety can be achieved.

(3) Modifications The power supply control device according to the present invention has been described above based on the embodiments. However, it goes without saying that the contents of the present invention are not limited to the above-mentioned embodiments. The following modified examples are possible.

In the above embodiment, the case where the drive system load is a motor has been described, but the present invention can be applied to other drive system loads such as a high voltage power supply.

In the above embodiment, DC / DC
Although the converter 201 is configured by using a high frequency transformer, a switching transistor, a rectifying diode, and the like, it may be configured by a series regulator, a dropper regulator such as a shunt regulator, or a step-down chopper such as a chopper type regulator.

Further, in the above embodiment, the output of the first DC power supply unit 100 is lowered to 9V in the power saving mode, but the drop voltage of the DC / DC converter 201 is small and 5V is output even if the input is about 5V. When the power saving mode can be maintained, the output voltage of the first DC power supply unit 100 in the power saving mode may be lowered to around 5V.
/ DC converter 201 is a charge pump type DC / DC
If the converter has a boosting function, the output voltage of the first DC power supply unit 100 in the power saving mode may be lowered according to the boosting function to further save energy.

In the above embodiment, the case where the output voltage of the first DC power supply section 100 is 24V and the output voltage of the second DC power supply section 200 is 5V in the normal mode has been described. Can also be applied to.

Further, in the above-mentioned embodiment, the case of using it in the copying machine has been explained, but it can be applied to other devices such as a facsimile and a printer.

[0030]

As described above, according to the power supply control device of the present invention, the first DC power supply means supplies the supply voltage to the first load and the second DC power supply means in the normal mode. Is set to the first voltage, and in the power saving mode, the supply voltage is set to a voltage lower than the first voltage and necessary for the second DC power supply means to output the second voltage. Therefore, the range in which the high first voltage is lowered can be set to be large, and the power consumption rapidly decreases as the square as the first voltage is lowered. Therefore, it is possible to eliminate the relay that was conventionally provided in the power supply path to the first load, and yet it is possible to save energy while ensuring the power supply to the control system load.

Further, the first DC power supply means receives a command to increase the voltage to the first voltage in the normal mode and a command to decrease the voltage to less than the first voltage in the power saving mode. Since the voltage control means for controlling the supply voltage is provided, the configuration of the first DC power supply means can be simplified.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an overall configuration of a power supply control device and its vicinity.

[Explanation of symbols]

1 Power Supply Control Device 100 First DC Power Supply Unit 101 Diode Bridges 102, 106, 202 Smoothing Capacitor 103 High Frequency Transformer 104 Switching Transistor 105 Diodes 107, 108, 110, 111 Resistor 109 Relay 112 Power Supply Control Circuit 200 Second DC Power Supply Unit 201 DC / DC converter Vout1, terminal Vout2, GND terminal CNT Power saving mode signal FB Voltage feedback signal QB Transistor switching signal ref1 24V output command ref2 9V output command RL5 Control system load RL24 Drive system load

Claims (2)

(57) [Claims] 1. A first load that operates when a first DC voltage is applied and that does not operate below a first DC voltage, and a second DC voltage that is less than a first DC voltage is applied. A second load that operates in a normal mode, operates both loads in a normal mode, and operates only the second load in a power saving mode. A first direct current power supply means connected to the second direct current power supply means;
A second direct current power supply means connected to the load of the first direct current power supply means, and the first direct current power supply means includes the first direct current power supply means in the normal mode.
The supply voltage to be supplied to the second load and the second DC power supply means is set to the first voltage, and the supply voltage is less than the first voltage in the power saving mode, and the second DC power supply means is set to the second voltage. A power supply control device having a configuration in which the voltage is set to a voltage required to output the voltage. 2. The first DC power supply means receives a command to increase the voltage to the first voltage in the normal mode, receives a command to decrease the voltage to less than the first voltage in the power saving mode, and based on both commands. The power supply control device according to claim 1, further comprising: a voltage control unit that controls the supply voltage.